Apparatus for exploration drilling



INVENTOR ATTORNFY FRANK s. BERGSTROM `luly 20, 1954 Filed Sept. 6 1951 July 20, 1954 F. s. BERGSTROM APPARATUS FOR EXPLORATION DBILLING Filed sept.v e, 1951 2 Sheets-Sheet 2 FIG. 2

INVENTOR FRANK S. BERGSTROM ATTORNEY Patented July 20, 1954 UNITED `STATES PATENT OFFICE APPARATUS EOR EXPLORATION DRILLING Frank S. Bergstrom, Eveleth, Minn.

'Application September 6, 1951, Serial No. 245,341

This invention relates to apparatus for exploration drilling and has for its principal'object the recovery from drill holes of mineral samples which are accurately representative as to structure and composition of the mineral in place, the samples closely simulating the material lafter mining and crushing so that accurate and reliable physical and chemical tests can be made.

A further object is to provide a drilling apparatus which greatly increases the rate of drilling in difficult ground such, for example, as that encountered on the Mesabi and Cuyuna Ranges in the State of Minnesota where glacial deposits of coarse gravel and boulders make drilling dinicult and expensive, and where in many locations the structure of the ore formation is too hard to churn drill or of such nature that core drilling is not feasible.

My invention has been used with outstanding success in such difficult ground structures and these operations have demonstrated that the present invention constitutes a practical solution of the problem of recovering reliable test samples while greatly reducing the cost of the drilling by minimizing interruptions -and delays incident to rem-oval of drill rods from the hole and blasting when extremely hard structures are encountered.

The invention will be best understood byreierence to the accompanying drawings which illustrate, by way of example and not for the purpose of limitation, a preferred embodiment of my improved drilling apparatus.

Referring to the drawings:

Figure 1 is a side elevational View, partially in section, showing the principal elements of the drilling apparatus and with portions of some of the members broken away or separated to show parts otherwise concealed;

Fig. 2 is a detail elevational view .showing the drill pipe cross head member and supporting bridle therefor as viewed from the right of Fig. 1;

Fig. 3 is a part sectional and'part side elevational view showing portions of thefseveral drill members and casings on a somewhat larger scale;

Fig. 4 is a detailed elevational view showing the bridle support for one of the churn drillV hammers;

Fig. 5 is a fragmentary sectional View of the drill pipe and chopping bit through which the cuttings may be conducted by compressed air to the surface;

Fig. 6 is a fragmentary elevational view of the yoke and the associated supporting membersA for the fluid operated hammer for the pilotdrill rod,v

and

6 Claims. (Cl. Z55-1.4)

Fig. 7 is a longitudinal sectional view of the pilot drill hammer.

As shown in Fig. 1, I provide a main frame having leg members IU supporting a crown sheave Il over which'a hoist rope l2 is trained. The hoist operating mechanism may comprise a cathead I3 of common type operated by an air motor I4 through suitable speed reducing mechanism in a housing I5. To provide air under suitable pressure and at the required rate for ejecting the samples and other cuttings from the drill hole and for operating the drilling mechanisms, a motor-driven air compressor of suitable capacity is preferably located near the site of the drilling. Air under the required pressure is supplied to the drilling apparatus through a flexible conduit It having a branch il' extending to the air motor I4 under control of a valve i3. A branch I9 of the flexible air supply conduit extends to the drill casing under control of a valve 20 and other branches 2l and 22 extend to the upper end portion of the drill rod and uid operated hammer respectively as hereinafter more fully described.

As best shown in Fig. 3, the drilling mechanism Y includes `a small drill rod 23 carrying a chopping bit 24 on its lower end. This rod and bit, which may be called the pilot drill, are formed with an unobstructed axial passage which is open at the lower face of the bit and extends continuously through a string of such rods. A fluid operated hammer 25 is supported on a pair of vertical guides 26 and operatively connected to the upper end of this pilot drill. Communicating with the axial passage in the drill rod 23 at an elevation below the hammer 25 is a iitting 2? which is connected to and supplied with air from the branch 2| of the air supply conduit.

The pilot drill rod 23 extends coaxially within a drill pipe 28 carrying a chopping bit 28a on its lower end and the upper end section of the pipe 28 has a threaded connection with a hollow member 29 communicating at its upper end with a cross head iitting 30. This iitting is formed with a passage communicating with a flexible discharge conduit 3l and the latter, when samples of ore are being taken, is arranged to deliver air and cuttings to a sample receptacle v32. This receptable is closed at the top and has a side outlet opening connected by a conduit 33 to discharge air and any ground water that may be entrained with the air to a settling basin 34.

A drill pipe hammer 35 of common type is formed with a central bearing in which the drill pipe member 29 is slidable and is provided with a bridle 36 (Fig. 4) for detachably connecting the hammer to the rope l2. Striking collars 3l are formed respectively on the member 29 below the hammer 35 and on the fitting Si) above the hammer for transmitting the impact of the hammer to the drill pipe 28. A packing gland 38 is operative to seal the connection between the drill rod 23 and fitting 3G when the drill rod is in place and a threaded cap 38a may be substituted for the packing nut when the pilot drill is not in place, as when this drill is not required to expedite the sinking of the drill pipe 2S and casing.

A coaxial cylindrical casing 39 contains the drill pipe 28 and provides an annular passage for air extending down from the surface to the lower end of the casing. A larger casing 4l! may also be provided to extend to a suitable depth in the surface structure and to facilitate the sinking of the casing 39 to greater depths. At an elevation above the ground surface, the ceun ing 39 is provided with a pipe fitting di com nected to the air supply conduit i8 for supplying air under suitable pressure to the passage be tween the drill pipe and casing. Above the ntting lll, a member 42 of the casing 39 extends through a cylindrical opening in a casing hammer i3 and a packing gland it is provided to seal the upper end of the annular passage in the casing 39 against the exterior of the drill pipe 28. The hammer S3 is arranged to strike suitable collars formed respectively on the tting il and packing gland 44, and a bridle, like the bridle 36 shown in Fig. 4, is provided to detachably connect the hammer 43 to the rope I2.

As shown in Figs. l and 5, the guides 2E for the hammer are supported on a yoke 45 mounted on the upper end portions of vertical frame members 46. Since iluid operated harnmers suitable for my purpose are well known in the art, it is sufficient to point out that the hammer 25 is of the percussion type having a iluid operated piston 25a of diameter adequate to perform the required drilling in hard rock. and ore formations with the pilot drill rod 23. The upper end of this rod may be operatively connected by means of a chuck 25h to the front head 25e of the hammer.

The following are given as examples of suitable proportions and dimensions of the air passages and drill member. For a hollow drill rod 23 of approximately 11/4 inch outside diameter an air hammer supplied with air at 80 to 100 pounds per square inch and having a piston diameter of approximately Il inches may be used. Such a pilot drill rod may be operated in a-drill pipe 28 of approximately 21/4 inches inside diameter. The outside diameter of the drill pipe may be equal to approximately 2.875 inches to operate in a casing 39 having an inside diameter of approximately 3.364 inches and thereby provide an annular passage suitable to conduct air at the required rate downward to the face of the drill hole and upward through the unconstricted and unobstructed axial passage of about 2% inches diameter in the drill pipe to the surface. Connecting passages of somewhat larger sizes are preferably provided through the cross head 3@ and discharge pipe 3 l. The air should be supplied at a rate and pressure suiiiciently high to cause it to flow through the described passages at a Velocity of from 250 to 300 feet per second.

Operation In drilling through surface soil to the depth of the ore deposits to 'be explored and in some ore structures it is often feasible to proceed without using the pilot drill rod 23 and its operating mechanism, the cap 38a being used on the fitting 30 to close the opening through the packing gland 38 for the rod 23. Until such time as samples of the ore structure are to be collected, the cuttings may be blown to waste through the discharge conduit 3l after merely disconnecting this conduit from the receptacle 32. In operation, the drill pipe 28 and casing 39 may be driven according to the churn drill method, that is to say, by alternately raising and dropping the string of drill pipe 28 carrying the chopping bit 28a with the aid of the hammer 35 operatively connected to the rop i2, the drill pipe being turned about its axis by manipulating the cross head Sil in the usual manner. The winding of this rope on the rotating cathead i3 and release allowing the hammer and pipe string to drop is controlled by the operator manually in accordancewith the common method of churn drilling. After. thus driving the drill pipe 23 down a suit-v able distance, e. g., from about one to two feet belen/.the casing S9, the casing is driven down in a similar manner to a depth substantially equal to the depth of the bit 28a. During and/or after each such advance of the drill pipe and casing the cuttings and loose material upon and above the face of the hole are ejected and the face cleaned by admitting high pressure air from the conduit E9 to the annular passage between the casing 3% and drill pipe 2S so that the air ilows at the required high velocity down through the annularv passage and then upward through the axial passage through the pipe '26 which communicates at its upper end through the tting 3i) with the discharge conduit 3i, carrying with it all loose material of particle sizes smaller than the inside diameter of the drill pipe 2S. Since the axial passage through the drill pipe is unobstructed and vof uniform maximum diameter through its length, relatively coarse cuttings pass freely to the discharge pipe in the high velocity stream of air flowing upward from the face of the hole. During this operation such ground water as may have entered the hole is also ejected by the air.

When a boulder or other obstruction of such hardness, size, location and shape as to prevent penetration of the chopping bit 23a is encountered, such obstruction may be broken up by the use of an explosive charge lowered through the drill pipe or by inserting the drill rod 23 through the pipe 2S and operating the hammer 25 to drill a pilot hole through the obstruction for enlargement either by churn drilling with the bit 28a or the pilot drill may be driven to a depth suitable to receive a charge of blasting powder or dynamite. Because of its relatively small size and high speed percussion operation, the pilot drill will penetrate extremely hard obstructions rapidly and may be withdrawn from the drill pipe in cases where a blasting charge is to be lowered thrugh the drill pipe. During the use of the pilot drill, air is forced down through its axial passage which is supplied with air through the tting 2l' and branch conduit 2i. The drill pipe and casing may be retained in the hole during the blasting if they are raised and supported a short distance above the explosive charge.

Usually after the removal of the obstruction in the manner described, sinking of the hole by the churn drill method may be resumed. The cu*- tings from the drill rod bit are forced upward by the air into the annular space between the 5 drill rod 23 and the drill pipe 28 and from this space such loose material and the material broken up by blasting may be recovered through the drill pipe as hereinbefore described.

Upon reaching the ore deposit to be explored, the sample discharge conduit 3| is connected to the receptacle 32 so that all cuttings may be recovered and tested for values and structure. Samples are taken at regular intervals as the drilling progresses, the drilling being carried on as hereinbefore described, i. e., by alternately driving the drill pipe 28 and casing 39 by increments of substantially equal depths, recovering the cuttings by forcing air downward between the casing and drill pipe and then up through the clear axial passage in the drill pipe and out through the tting 30 and discharge pipe 3| to the receptacle 32. This proceeding is repeated until the hole has been completed to the required depth. The samples thus recovered are in particles of a range of sizes corresponding approximately to those obtained by crushing and there is a minimum of leaching and loss of water soluble constituents. Anf7 ground water that may be entrained with the air is separated from the samples and carried through the conduit 33 into the settling basin 3'4. Such ne cuttings as may be carried into the settling basin 34 are also readily recoverable for test purposes.

It will be evident that the present invention has the important advantage over other exploration methods and apparatus in that the samples recovered simulate the material after mining and crushing and thus constitute the basis for accurate physical and chemical tests. Cuttings of sizes ranging up to approximately the inside diameter of the drill pipe are obtained and the air eiecting medium, unlike water, does not leech out soluble constituents of the ore or otherwise alter the structure or composition of the material in place. The rate of drilling is increased by eliminating the need for reducing the cuttings to iine particles in order to recover them and also as a result of the increased rate of drilling with a high speed percussion operated pilot drill which facilitates blasting through obstructions at predetermined sample intervals so that the casing may be driven down while sampling or while ejecting waste cuttings and sludge from the hole.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

l. Drilling apparatus comprising, a hollow drill rod, a hollow drill pipe containing said drill rod below ground, said pipe forming a substantially clear, unobstructed passage for cuttings and having an intake opening which is adapted to receive cuttings near the face of the drill hole, a casing containing said drill pipe below ground, percussion means for sinking said'rod, pipe and casing independently one relative to the others whereby said drill rod may be operated in advance of the drill pipe and the lower end of the casing may be maintained at a level substantially even with the lower end of the drill pipe, said drill rod being removable from the axial passage in said drill pipe and the passage in said pipe being formed to conduct cuttings from the face of the hole to the surface, means for supplying air under pressure to the annular space between the casing and drill pipe, said annular space communicating with the axial passage in the drill pipe near the face of the hole and a conduit communicating with the axial passage in drill pipe exteriorly of the hole to discharge air carrying cuttings from the hole.

2. Drilling apparatus in accordance with claim 1 wherein the percussion means for driving said rod comprises a iiuid pressure operated piston and means operatively connecting said piston to the upper end of said drill rod.

3- Drilling apparatus in accordance with claim l wherein the percussion means for sinking said rod comprises a uid pressure operated hammer and the percussion means for sinking said drill pipe and casing comprises churn drilling mechanism adapted to be operated to alternately sink said pipe and casing,

4. Drilling apparatus comprising, a hollow drill rod, a hollow drill pipe having an axial adapted to contain said drill rod below ground, a casing adapted to contain said drill pipe beiow ground, percussion means for driving said rod, pipe and casing, said drill rod being removable from the axial passage in said drill pipe and the passage in said pipe being substantially uniform in diameter throughout its length and .having an intake opening which is adapted to be positioned near the face of the hole whereby cuttings from the face of the hole may be discharged upward through said axial passage to the surface, means for supplying air under pressure to the annular space between the casing and drill pipe, said annular space communicating with the axial passage in the drill pipe near the face of the hole, a conduit communicating with the axial passage in said drill pipe exteriorly of the hole and a receptacle disposed to receive cuttings and air from said conduit.

5. Drilling apparatus comprising, a` drill rod, a hollow drill pipe adapted to form a hole and having an axial passage adapted to contain said drill rod below ground, a casing adapted to contain said drill pipe below ground, percussion means for driving said rod, pipe and casing, said drill rod being removable from the axial passage in said drill pipe, the passage in said pipe being formed to conduct cuttings from the face of the hole to the surface and having an intake opening adapted to be positioned adjacent to the face of the hole, means for supplying a iiuid under pressure to the annular space between the casing and drill pipe, said annular space being in communication near the face of the hole with the axial passage in the drill pipe, a conduit communicating with the axial passage in said drill pipe exteriorly of the hole and a receptacle disposed to receive cuttings and iiuid from said conduit.

6. Drilling apparatus in accordance with claim 5 wherein the percussion means for driving said rod comprises a fluid pressure operated piston and means operatively connecting said piston to said drill rod.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,071,199 Andrews Aug. 26, 1913 2,132,717 Beckman Oct. 11, 1938 2,342,253 Cooley 1 Feb. 22, 1944 2,540,385 Biggs Feb. 6, 1951 2,595,126 Causey Apr. 29, 1952 

